Formation of the herpes simplex virus (HSV) envelope, and egress of enveloped virions from cells, is critical for the production of infectious particles and the spread of disease. Unfortunately, little is know of how HSV capsids and tegument proteins refashion cell membranes into envelopes. Similarly, the identity of the cytoplasmic organelles utilized for viral exocytosis remains obscure. Our working model is that HSV capsids acquire their final envelope in the cell cytoplasm by attaching to the surface of the Golgi apparatus or endosomes, then budding into them. Using novel assay techniques developed in this laboratory, we will purify then establish the identity and function of cytoplasmic organelles utilized for HSV envelopment. The mechanism of association of capsids and tegument proteins with the surface of these organelles, the first step in viral envelopment, will then be determined. Finally, the interaction of capsids with cytoplasmic compartments will be visualized in living cells by imaging the trafficking of Green Fluorescent Protein tagged capsids during a single, synchronized wave of assembly. Information obtained from this study will help in the design of agents able to interfere with HSV envelopment, thus reducing the virulence of this serious human pathogen.